Scavenge system



Jan. 2l, 1947. A. KALlTlNsKY 2,414,744

l SCAVENGE SYSTEM Filed May 11, 1945 2 sheets-sheet 1 l FIG. l

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SCAVENGE SYSTEM Filed May ll; 194:3I 2 Sheets-Sheet 2 wr INVENTOR @MMM `Mm` ATTORNEY Patented Jan. 21, 1947 Andrew lalitinsky,

United Aircraft Corporation,

Eagleville, Conn., assigner to East Hartford,

Conn., a corporation of Delaware Application May 11, 1943, Serial No. 48.6,6l6

Slairns. l

This invention relates to the scavenging of twocycle engines.

In a free-piston engine-and-compressor unit the air from the compressor may scavenge the engine cylinder, and the engine exhaust gases may be used for driving a turbine. In these circumstances, there `is necessarily a substantial pressure difference between the scavenge and exhaust manifolds, and the `maximurn exhaust pressureA islimited by the scavenge Pressure andthe pressure difference between the manifolds. The compressonhowever, supplies more air than is necessary for satisfactory scavenging. A feature of this invention is the automatic bypassing, directly to the exhaust manifold, of the air not needed for scavenging, therein?,1 increasing the exhaust pressure.

The bypass connection, in accordance with this invention, is adjacent the engine cylinder1 in order to cool the engine cylinder andsimultaneously heat the bypassed air to increase the total heat content of the gases in the exhaust manifold.

The scavenge and exhaust ports of the engine cylinder may be closely spaced, with an exhaust manifold receiving gas from the exhaust ports and an adjoining scavenge manifold directing compressed air through the scavenge ports. Since there is an excess of .scavenge4 air, which may be admitted directly to the exhaust manifold without passing through the engine cylinder, a feature of this invention is the interconnection of the manifolds by spacing the manifolds from the cylinder wall between the exhaust and scavenge ports, thereby providing a passage for bypassing some scavenge air. This spacing of the manifolds also permits the desired close spacing of the ports.

Another feature of of a single dividing wall for enge and exhaust manifolds folds may be closely spaced. In accordance with the invention, the inner edge of the dividing wall is free from any direct connection with the engine cylinder and may permit the bypassing of scavenge' air around the edge of this wall. This bypassedair helps to cool the cylinder wall between the ports.

Other objects and advantages will be apparent from-the specification and claims, and from the accompanying drawings which illustrate what is now considered to be a preferred embodiment of the invention.

Fig. 1 is a sectional view through the free-piston engine-and-compressor unit.

Fig. 2 is an enlarged fragmentary sectional View this invention is the use the adjacent scavso that these maniof a part of the engine cylinder and the manifolds showing the engine cylinder in greater `detail. n

The unit shown includes an enginge cylinder ill having reciprocating `pistons l2 and i4 to which compressor pistons iE and I8 in cylinders 2t and 22 are integrally connected. Sleeves 24 and 25 attached to the compressor pistons com,- plete the reciprocating piston assemblies. The sleeves reciprocate over stationary pistons 28 and 3B and form air .spring cylinders.

The piston-assemblies are moved apart by the burning of fuel injected into engine cylinder ID by one or more devices 32. Air compressed in the air spring cylinders on the power stroke returns the piston assemblies. The piston assemblies are maintained always at equal distances from the center of the engine cylinder by a linkage, whichmay include the racks 34 on the compressor piston engaging opposite sides of a pinion 36.

Intake manifold 38 conducts air to intake valves 4i) through which air alternately` enters opposite ends of the compressor cylinders. The compressed air `leaves the'cylinders through discharge valves 42, also at opposite ends of the compressor cylinders, and passes into the engine cylinder through scavenge manifold 44 and ports lo and 48 which are uncovered by pistons i2 and i4 at the end of the power stro-ke thereby permitting air to be blown through the engine cylinder and exhaust ports 5l) and 52 into exhaust manifold 54. The compressors shown are double acting and normally provide more scavenge air than is necessary for satisafactory scavenging of the engine.

The scavenge ports 4t and 48 (Fig. 2) are adjacent opposite ends of the engine cylinder. Each port consists of a number of openings which communicate with ring-shaped ducts 5&6 and v.38 surrounding the cylinder. YThese ducts form parts of the scavenge manifold.

The exhaust ports 50 and 52 are also adjacent opposite ends of the engine cylinder and between the spaced scavenge ports. Each exhaust port consists of a number of openings Which communicate with annular ducts Eil and B2 surrounding the cylinder. The ducts form parts of the exhaust manifold.

The close spacing of either series of exhaust openings to the adjacent scavenge openings per.- mits the use of single ring-shaped dividing walls 64 `and 66 between scavenge and exhaust mani-Y folds. Walls 64 and $6 form partitions between ducts 56 and (i0 and ducts 58 and S2 respectively.

The inner edgesv 68 and 10 of walls 64 and 66 are free from direct connection to the engine cylinder.

Compressed air discharging around the inner edge of walls 64 and 66 cools the engine cylinder at a part where cooling is very important and also increases the pressure in the exhaust manifold thereby Aimproving the operation of the unit. The spacing of the inner edges of Walls 64 and 66 from the engine cylinder may be accurately proportioned to allow bypassing of the i! desired amount of air. -1

.It is to be understood that the invention is not limited to the specific embodimentherein illustrated and described, but may be used' in other ways without departure from its spirit as defined by the following claims.

I claim:

1. In an engine, a cylinder having scavenge and exhaust ports adjacent each other, and manifolds for the ports, said manifolds being spaced from the engine cylinder between the ports to provide a bypass for scavenge air from `the scavenge manifold to the exhaust manifold.

2. In an engine, a cylinder having scavenge and exhaust ports adjacent each other, and manifolds for the ports, said manifolds including a partition extending around the cylinder between the ports, vsaid partition being free `from directl connection with the engine cylinder.

3. In an engine, a cylinder having scavenge and exhaust ports adjacent each other, and manifolds for the ports, said manifolds being free from direct connection with the engine cylinder between the ports and communicating with each other for bypassing a quantity ofscavenge air directly to the exhaust manifold.

4. In a supercharged engine, a cylinder having adjacent scavenge and exhaust ports, and a manifold for each port, said manifolds having a passage adjacent the cylinder permitting a predetermined flow of scavenge gas directly to the -exhaust manifold.

" 5. In a supercharged engine, a cylinder having scavenge and exhaust ports adjacent each other and manifolds for the ports, said manifolds having a common wall adjoining the cylinder, the 'inner edge of said wall being free from direct attachment to the cylinder.

6. In a supercharged engine, a cylinder having scavenge and exhaust ports adjacent 'each other and manifolds for the ports, said manifolds having a common wall adjoining the cylinder, the inner edge of said wall being spaced from the cylinder to define a bypass for scavenge air to the exhaust manifold.

7. In a free-piston engine-and-compressor unit, an engine cylinder having scavenge and exhaust ports adjacent each other, a'piston reciprocating in said cylinder, a compressor cylinder and a compressor piston, one of which is connected to the engine piston, manifolds for the scavenge and exhaust ports and a connection between `manifolds adjacent the engine cylinder for the discharge of a predetermined quantity of scavenge gas from the compressor directly to the exhaust manifold.

8. In a free-piston engine-and-compressor unit, an engine cylinder having scavenge and exhaust ports adjacent each other, a piston reciprocating in said cylinder, a compressor cylinder and a compressor piston, one of which is connected to the engine piston,` a manifold connecting the discharge valves of the compressortothe scavenge port, an exhaust manifold, and a passage from the scavenge manifold to the exhaust manifold adjacent the engine cylinder. Y

9. In a free-piston engine-and-compressor unit, an engine cylinder having scavenge and exhaust ports adjacent each other, a piston reciprocating in said cylinder, a compressor cylinderV and a compressor piston, one of which is connected to the engine piston, a manifold connecting the discharge valves of the compressor to the scavenge port, an exhaust manifold, said manifolds being located adjacent each other and having a common dividing wallfthe inner edge of which is free from direct connection to the engine cylinder. l

` 10. In a free-piston engine-and-compressor unit, an engine cylinder having scavenge and exhaust ports adjacent each other, a piston reciprocating in said cylinder, a compressor cylinder and a compressor piston, one of which is connected to the engine piston, a manifold connecting the discharge valves of the compressor to the scavenge port, an exhaust manifold, said manifolds being located adjacent each other and having a common dividing wall closely spaced from the engine cylinder to dene a passage for the discharge of a predetermined quantity of scavenge air directly to the exhaust manifold.

ANDREW KALITINSKY. 

